In the recent years, the electronic component pick-and-place equipment is in many cases operated for batch production in terms of the flexible manufacturing system (wide-variety-of-types, low-volume production) and for environmental improvement for the production of printed circuit boards. As a result, there have arisen cases, in particular, where boards are transferred to and from a board stock rack and the electronic component pick-and-place equipment by using one robot. In the board transfer method and apparatus of this return-back system, advantageously, the installation space can be saved, while one robot will be sufficient for both the transfer of a board prior to component placement and the transfer of a board after the component placement, because the board after the component placement is returned to the position from where the board prior to component placement was transferred.
Conventionally, a board transfer apparatus of the return-back system as shown in FIG. 10 comprises a pair of guide rails 2 having a drive device for guiding and transferring a board 1, a link mechanism 3 for supporting the guide rails rotatably about a fulcrum, an air cylinder 4 for driving the link mechanism 3 to rotate about the fulcrum and thereby move the guide rails 2 up and down, and an X-Y table 5 for positioning the board.
With this arrangement, the board 1 on the X-Y table 5 after the component placement thereon is transferred onto the guide rails 2 that have been lowered by the air cylinder 4 and coupled with rails of the X-Y table 5. The board 1 is then moved to the other end of the guide rails 2. Subsequently, the board 1 after the component placement thereon is removed by a robot or the like, and then a board prior to component placement thereon is newly placed on the guide rails 2.
Next, the board prior to component placement thereon is transferred onto the X-Y table 5, and the guide rails 2 are driven by the air cylinder 4 so as to be moved up, and thereby separated from the X-Y table. This is the process in which boards are exchanged and transferred.
In such a conventional board transfer apparatus, on the X-Y table 5, the board 1 after the component placement thereon is transferred from the X-Y table 5 via the guide rails 2, and thereafter, a board prior to component placement thereon is transferred to the X-Y table via the guide rails 2. Therefore, much time is required for the replacement of boards, which has been an obstacle to reducing the production cycle time.